Green Mask
© INAHA detailed green stone mask unearthed beneath Mexico's Pyramid of the Sun may be a portrait of a specific individual.

Archaeologists in Mexico have uncovered a small treasure trove of items that may have been placed as offerings to mark the start of construction on the Teotihuacan Pyramid of the Sun almost 2,000 years ago.

The offerings include pieces of obsidian and pottery as well as animal remains. Perhaps most striking are three human figurines made out of a green stone, one of which is a serpentine mask that researchers think may have been a portrait.

The Pyramid of the Sun is the largest structure in Teotihuacan, an archaeological site northeast of Mexico City that dates back to about 100 B.C. The city remained populated for hundreds of years, and the residents likely started to build the Pyramid of the Sun around A.D. 100.

Beheaded human remains, possibly sacrifices, were found nearby in the Pyramid of the Moon in 2004.

Archaeologists with Mexico's National Institute of Anthropology and History (INAH) have been excavating within the pyramid for the last several years, digging 59 holes and three short tunnels in search of offerings and burials. They've uncovered seven human burials, some of them infants, that even predate the Pyramid of the Sun structure.

The researchers also found two offerings - one containing the green mask and another offering - in the base of the pyramid, "so we know that was deposited as part of a dedication ceremony," Perez Cortez, an investigator with the Zacatecas INAH Center, said in a statement.